cysteinylleukotrieenit

Cysteinylleukotrieenit are a group of potent lipid mediators derived from arachidonic acid. They play a significant role in inflammation, particularly in allergic responses and asthma. These molecules are synthesized from leukotriene A4 (LTA4) by the enzyme leukotriene C4 synthase. LTA4 is produced via the lipoxygenase pathway, which begins with the activation of phospholipase A2.

The primary cysteinylleukotrieenit are leukotriene C4 (LTC4), leukotriene D4 (LTD4), and leukotriene E4 (LTE4). These compounds are sequentially converted from one form to another by enzymatic action. LTC4 is released from cells and then rapidly converted to LTD4 by gamma-glutamyl transpeptidase. LTD4 is further metabolized to LTE4 by dipeptidases.

Cysteinylleukotrieenit exert their effects by binding to specific G protein-coupled receptors, primarily the cysteinyl leukotriene receptor 1 (CysLT1R). Activation of CysLT1R leads to a cascade of cellular events, including bronchoconstriction, increased vascular permeability, mucus hypersecretion, and the recruitment of inflammatory cells such as eosinophils and T lymphocytes to the airways. This contributes to the pathophysiology of asthma, causing airway narrowing and inflammation. They are also implicated in other inflammatory conditions. Antagonists of the CysLT1R, such as montelukast and zafirlukast, are used clinically as controller medications for asthma due to their ability to block these pro-inflammatory effects.